Ch.16 – Test Bank – Kinetics What Affects The Speed Of A

Chapter 16: Kinetics: what affects the speed of a reaction?

Test Bank

Type: multiple response question

Title: Chapter 16 - Question 01

1) Which of the following statements about the rate of a chemical reaction are true? Select all that apply.

a. The rate of a chemical reaction depends on the Gibbs free energy change of the reaction.

b. The rate of a reaction is given by calculating the change in concentration of a compound divided by the time.

c. The rate of a chemical reaction is constant for any particular reaction.

d. The rate of a chemical reaction varies with temperature.

e. The rate of a chemical reaction varies according to the reaction vessel used.

Type: multiple choice question

Title: Chapter 16 - Question 02

2) The decomposition of a solution of hydrogen peroxide, H₂O₂, was monitored over several days. Initially, hydrogen peroxide was present at a concentration of 1 mol L^-1; after four days the hydrogen peroxide was present at a concentration of 0.5 mol L^-1. What is the rate of the reaction for the decomposition of hydrogen peroxide?

a. 1.40 × 10^-6 mol L^-1

b. 1.40 × 10^-9 mol L^-1 s^-1

c. 1.40 × 10^-6 mol L^-1 s^-1

d. 1.25 × 10^-1 mol L^-1 day^-1

e. 8.68 × 10^-5 mol L^-1 min^-1

Type: multiple response question

Title: Chapter 16 - Question 03

3) Which of the following factors affect the rate of a chemical reaction? Select all that apply.

a. The Gibbs free energy change of the reaction.

b. The temperature at which the reaction occurs.

c. The concentration of the reactants.

d. The presence of a catalyst.

e. The entropy change of reaction.

Type: multiple choice question

Title: Chapter 16 - Question 04

4) The activation energy of a reaction is equal to which of the following?

a. The energy of the reactants.

b. The energy of the transition state.

c. The Gibbs free energy of the reaction.

d. The energy of the products.

e. The enthalpy change of the reaction.

Type: multiple response question

Title: Chapter 16 - Question 05

5) Which of the following correctly describes the effect of a catalyst on a chemical reaction? Select all that apply.

a. It increases the rate of the forward reaction.

b. Catalysts decrease the rate of the back reaction.

c. Catalysts lower the activation energy of a reaction.

d. Catalysts decrease the time required for equilibrium to be established.

e. Catalysts never allow equilibrium to be reached

Type: multiple choice question

Title: Chapter 16 - Question 06

6) When the temperature of a reaction is increased, the rate of the reaction is also increased. Which of the following is the correct reason for this?

a. The Gibbs free energy of the reaction is lowered.

b. The activation energy is lowered.

c. The number of molecular collisions is increased.

d. The kinetic energy of the system is lowered.

Type: multiple response question

Title: Chapter 16 - Question 07

7) In order to function at maximum efficiency, enzymes often require which of the following? Select any that apply.

a. To be heated.

b. To be flexible.

c. To be in an environment with a particular pH.

d. To have an active site whose shape is complementary to the product(s) of the reaction.

Type: multiple choice question

Title: Chapter 16 - Question 08

8) The units used to express the rate of a chemical reaction are which of the following?

a. mol s^-1

b. mol L^–1 s^-1

c. L mol^–1 s^-1

d. s mol^–1

e. s mol^-1 L^–1

Type: multiple response question

Title: Chapter 16 - Question 09

9) Which of the following statements concerning the action of a catalyst are true? Select all that apply.

a. Catalysts alter the enthalpy change of a reaction.

b. Catalysts are normally consumed during the course of a reaction.

c. Catalysts provide an alternative mechanism for the reaction.

d. Catalysts do not take part in the reaction that they speed up.

e. Catalysts lower the activation energy of a reaction.

Type: multiple choice question

Title: Chapter 16 - Question 10

10) Which of the following statement about enzymes is true?

a. Enzymes increase the rate of a chemical reaction by eliminating the activation energy.

b. Most enzymes are nucleic acids.

c. Enzymes can distinguish between enantiomers.

d. Enzymes are rarely specific for the reactions they catalyse.

e. Enzymes are rigidly fixed into a specific three-dimensional structure.

Type: multiple response question

Title: Chapter 16 - Question 11

11) Which of the following graphs depict a reaction proceeding at a constant rate? Select all that apply.

a.

b.

c.

d.

e.

f.

Type: multiple choice question

Title: Chapter 16 - Question 12

12) The concentration of a compound, X, is measured at different time intervals during the course of a chemical reaction. After plotting a graph of the concentration of X against time, shown in the graph below, the points labelled A-E on the graph have the following co-ordinates:

A: x = 0 seconds; y = 0 mol L^-1

B: x = 8 seconds; y = 0.37 mol L^-1

C: x = 15 seconds; y = 0.49 mol L^-1

D: x = 23 seconds; y = 0.63 mol L^-1

E: x = 30 seconds; y = 0.62 mol L^-1

What is the rate of the chemical reaction after the reaction has been proceeding for fifteen seconds?

a. 3.26 mol L^-1 s^-1

The slope of the tangent is calculated by taking the differences between the values of the concentration and time at points B and D, recalling that .

So, in this case,

b. 0.017 mol L^-1 s^-1

The slope of the tangent is calculated by taking the differences between the values of the concentration and time at points B and D, recalling that .

So, in this case,

c. 0.021 mol L^-1 s^-1

The slope of the tangent is calculated by taking the differences between the values of the concentration and time at points B and D, recalling that .

So, in this case,

d. 57.7 mol L^-1 s^-1

The slope of the tangent is calculated by taking the differences between the values of the concentration and time at points B and D, recalling that .

So, in this case,

e. 48.39 mol L^-1 s^-1

The slope of the tangent is calculated by taking the differences between the values of the concentration and time at points B and D, recalling that .

So, in this case,

Type: multiple choice question

Title: Chapter 16 - Question 13

13) Look at the graph below. At which time point, A-D, is the reaction at its slowest?

a. A

b. B

c. C

d. D

Type: multiple choice question

Title: Chapter 16 - Question 14

14) An enzyme-catalyzed reaction can be represented by which of the following general equations?

a. E + S 🡪 ES 🡪 E + P

b. E + S ⇌ E + P

c. E + S ⇌ ES 🡪 P

d. E + S ⇌ ES 🡪 E + P

e. E + S ⇌ P

Type: multiple choice question

Title: Chapter 16 - Question 15

15) The following graph depicts the rate of an enzyme-catalyzed reaction. Which value, A-D, represents the Michaelis constant, K_M, for the enzyme featured in the graph?

a. A

b. B

c. C

d. D

Type: multiple choice question

Title: Chapter 16 - Question 16

16) Which one of the following statements is false when an enzyme is saturated?

a. The velocity of the reaction has reached V_max

correct

b. A further increase in substrate concentration leads to a decrease in velocity of the reaction.

c. The active site of every enzyme present is occupied.

d. The number of substrate molecules being processed by each enzyme molecule per second has reached the value of the enzyme’s turnover number.

Type: multiple choice question

Title: Chapter 16 - Question 17

17) The way in which the rate of a reaction depends on the concentration of its reactants is described by which of the following?

a. The free energy of the reaction

b. The rate constant

c. The order of the reaction

d. The half life of the reaction

Type: matching question

Title: Chapter 16 - Question 17

17) Match the type of enzyme inhibition with the observed effect on V_max and K_M

Feedback: Enzyme inhibitors affect V_max and K_M according to how they interact with the substrate and/or the enzyme active site. If the inhibitor competes directly with the substrate for the active site (as is the case for competitive inhibitors) the effect of the inhibitor on V_max can be overcome by increasing the concentration of substrate. This tactic doesn’t work, however, for non-competitive and uncompetitive inhibitors, both of which reduce V_max.

Page reference: Section 16.7

a. V_max is unchanged; K_M increases = Competitive inhibitor

b. V_max decreases; K_M is unchanged = Non-competitive inhibitor

c. V_max decreases; K_M decreases = Uncompetitive inhibitor